PROCESS FOR THE PREPARATION OF METHIONINE

Preparing D,L-methionine, comprises supplying carbon dioxide to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)-hydantoin, for precipitating crude methionine, separating the crude methionine, and purifying it by preparing an aqueous solution of the separated crude methionine, comprising potassium ions and a crystallization additive, which is a nonionic or anionic surfactant, and subjecting the solution to recrystallization, which is carried out by introducing a hot methionine solution into a warm methionine suspension. Preparing D,L-methionine, comprises supplying carbon dioxide to an aqueous potassium methioninate solution obtained by hydrolysis of 5-(2-methylmercaptoethyl)-hydantoin, for precipitating crude methionine, separating the crude methionine, and purifying it by preparing an aqueous solution of the separated crude methionine, comprising potassium ions and a crystallization additive, which is a nonionic or anionic surfactant, or a mixture of different nonionic or anionic surfactants, and subjecting the solution to recrystallization, which is carried out by introducing a hot methionine solution with a temperature of 60-110[deg] C, into a warm methionine suspension with a temperature of 35-80[deg] C, which is less than the temperature of the introduced solution. The temperature of the methionine suspension is held at 35-80[deg] C during the addition.